Please login or register.

Login with username, password and session length

Author Topic: Damn Wall Warts!  (Read 1125 times)

brobin

  • Hero Member
  • *****
  • Helpful Post Rating: 157
  • Posts: 1406
Damn Wall Warts!
« on: May 27, 2021, 02:55:15 PM »

Two nights ago I told Alexa to arm the alarm system before I went to bed.  Nothing, Nada, Zip.  I use a Smartenit Harmony as an Alexa bridge to my Stargate controller which normally works flawlessly.  I tell Alexa to turn something on and the Smartenit Harmony sends an X10 code to trigger the Stargate to do whatever it's supposed to do.

I went through the usual steps of checking connections, rebooting things and even trying a different PLM with the Harmony to no avail.  Then I pulled out my trusty XTBM Pro signal sleuth and plugged it into the same outlet as the Harmony.  BINGO!  It said "HIGH NOISE" which is something I've never seen before.  There is a Tivo Roamio on the same circuit as the Harmony so I unplugged the 12v 3a wall wart and the noise disappeared.  The wall wart is over 7 years old and still outputs the correct voltage but felt a bit warmer than it should be.  I replaced it with a 5 amp power supply and all is well again.  What I also noted is that if I plugged the wall wart back in by itself while watching the XTBM, there would be a very brief "HIGH NOISE" reading and then it was OK.  If the wall wart was also plugged into the TIVO then the noise remained constant so the load on the wall wart apparently has an effect on the noise level.

The moral of the story is that wall warts can and do go bad - at least from an X10 standpoint - before they completely fail.  I've had wall warts cause problems before but this is the first time in 37 years that I've had one change like this.
Logged

Brian H

  • Community Organizer
  • Hero Member
  • ***
  • Helpful Post Rating: 305
  • Posts: 13259
Re: Damn Wall Warts!
« Reply #1 on: May 27, 2021, 03:50:21 PM »

Thank you for the valuable information. One more thing to keep in mind.
I have seen reports of a wall wart making power line noise.
Cell phone chargers are another device I have seen reports on issues.
Jeff has a tutorial on a cell phone charger he tested. The noise was directly on the X10 120KHz power line frequency.
Logged

brobin

  • Hero Member
  • *****
  • Helpful Post Rating: 157
  • Posts: 1406
Re: Damn Wall Warts!
« Reply #2 on: May 27, 2021, 04:40:37 PM »

I'm the guy that many years ago sent that Cellet cellphone charger to Jeff that he wrote about in that tutorial. http://jvde.us/x10/x10_cellet_noise.pdf
 It was the wall wart from hell!  After he tested it he asked me if I wanted it back.  I told him to keep it - I didn't want it anywhere near me!  That one was trouble right out of the box.  The TIVO one took 7 years to act up.  :o
Logged

AMXoldhack

  • Full Member
  • ***
  • Helpful Post Rating: 0
  • Posts: 42
Re: Damn Wall Warts!
« Reply #3 on: June 11, 2021, 08:04:55 PM »

I try to avoid switch mode wall warts when ever possible. I find especially the cheaper ones extremely noisy. I always put a filter between them and a outlet.
Logged

bkenobi

  • PI Expert
  • Hero Member
  • ******
  • Helpful Post Rating: 24
  • Posts: 2081
Re: Damn Wall Warts!
« Reply #4 on: June 11, 2021, 10:49:05 PM »

I try to avoid switch mode wall warts when ever possible. I find especially the cheaper ones extremely noisy. I always put a filter between them and a outlet.

I see people make that statement frequently when discussing signal noise.  While I definitely agree, I find it very difficult these days to find power supplies that are NOT switching.  The way we buy products these days, it's not possible to look at the specs on the box or the module itself.  We can only go by what the online ad provides as specs which doesn't always give enough info.  If it says 110/220vac input, it's a fair bet it's switching but it's not uncommon for the listing to simply provide the the output DC voltage and leave the buyer to assume the input requirements. 
 

X10.com | About X10 | X10 Security Systems | Cameras| Package Deals
© Copyright 2014-2016 X10.com All rights reserved.